21478986 has 16 divisors (see below), whose sum is σ = 47731200. Its totient is φ = 7159644.

The previous prime is 21478979. The next prime is 21479011. The reversal of 21478986 is 68987412.

It is a super-2 number, since 2×21478986² = 922693679176392, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198826 + ... + 198933.

It is an arithmetic number, because the mean of its divisors is an integer number (2983200).

Almost surely, 2^21478986 is an apocalyptic number.

21478986 is an abundant number, since it is smaller than the sum of its proper divisors (26252214).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21478986 is a wasteful number, since it uses less digits than its factorization.

21478986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397770 (or 397764 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21478986 is about 4634.5426958870. The cubic root of 21478986 is about 277.9742656854.

The spelling of 21478986 in words is "twenty-one million, four hundred seventy-eight thousand, nine hundred eighty-six".